EP1234117B1 - Shockproof mechanism, in particular for use in space sector - Google Patents

Abstract

The mechanism includes a low melting point material (300) such as paraffin or a eutectic alloy, at least one electric or highly exothermal pyrotechnical composition heater (400), and a device suitable for throttling the low melting point material (300) in the liquid state, after the heater is actuated, thus performing a shock-absorbing function. The device further includes at least two concentric surfaces (154, 216; 152, 218) defining, a set of clearances between them and provided respectively on ring and piston parts (150, 200) that are capable of moving in order to throttle the low melting point material (300) through the set of clearances defined between the concentric surfaces. - Before an electrical initiator (180) is used to initiate the pyrotechnical composition, the soldered connection constituted by the low melting point metal at the interfaces between a cylindrical part 156 and the middle diameter piston segment (216) and between the another cylindrical part 152 and the largest diameter piston segment (218), and also the solid phase of this metal situated inside the a chamber (310), provides reliable and effective blocking of the structure ensuring that two assemblies (100 and 200) are prevented from moving relative to each other, with a ring (150) being prevented from moving relative to a body (110) and to a plug (130). In this position, the small section (214) of the piston (200) can emerge at least in part to the outside of the assembly (100). When the electrical initiator (180) is powered, the pyrotechnical composition is triggered to rapidly raises the temperature of the metal to melt it, thereby releasing the piston relative to the assembly (100). The gas coming from the chemical reaction of the pyrotechnical composition causes the chamber (220) to expand and thus moves the piston away from the plug in translation along the axis O-O. This displacement of the piston reduces the volume of the chamber (310) and thus transfers the low melting point metal by throttling it between the adjacent surfaces of the ring (150) and of the piston, thus performing a damping function on the movement. The low melting point metal then re-solidifies to reconstitute the solder connection and finally block the device in a new state in which the piston extends further from the second end of the body (100) than it did in the initial state.

Description

The present invention relates to the field of mechanisms actuated by a thermal effect.

The present invention finds in particular, but not exclusively, application in the space industry, for example on launchers or satellites, in particular in the form of shears, valves, cuts strap, etc ...

The means actuated by a known thermal effect, in particular the known pyrotechnic means, offer great possibilities. They in particular have a high potential between energy supplied and mass on board, as well as high reliability.

However, these mechanisms also have a drawback major: the great dynamics induced by their functioning.

Indeed, the shock and vibration levels are often prohibitive to the use of fragile equipment near them.

Document EP-A-0 311 026 is known, moreover, a mechanism comprising a heating means for generating a shock absorbing function. The regulation electric heating means is however expensive to implement.

The object of the present invention is to propose a new mechanism which does not have the aforementioned drawbacks.

This object is achieved in the context of the present invention, thanks to a equipment according to claim 1 appended, which is delimited in the form of a preamble and of a characterizing part compared to EP-A-0 311 026.

• la figure 1 représente schématiquement une structure conforme à la présente invention, sous forme d'un actionneur linéaire vue en coupe axiale partielle longitudinale, et
• les figures 2 à 5 représentent quatre variantes de réalisation de mécanismes conformes à la présente invention.

Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the appended drawings, given by way of nonlimiting examples and in which:

• FIG. 1 schematically represents a structure in accordance with the present invention, in the form of a linear actuator seen in partial longitudinal axial section, and
• Figures 2 to 5 show four alternative embodiments of mechanisms according to the present invention.

We will first describe the structure of the illustrated linear actuator in Figure 1 attached.

The system illustrated in the appended FIG. 1 comprises essentially a structure consisting of two sets 100, 200 susceptible of relative displacement, a block 300 of metal at low point of fusion and a highly exothermic pyrotechnic composition 400.

In the present case, the two sets 100, 200 are susceptible of relative translation along the central axis O-O of the structure.

The first set 100 is composed of three parts: a body 110, a stopper 130 and a ring 150.

The body 110 is generally cylindrical of revolution around the O-O axis. More specifically, the body 110 has a central internal channel 112 storied. The channel 112 is divided, according to FIG. 1, into three sections 114, 116, 118, juxtaposed axially.

Section 118 having the largest internal diameter, adjacent to a first end of the assembly 100 is provided with a tapping 119 over part of its length. The internal thread 119 is complementary to a thread 132 provided on the plug 130.

Section 114 with the smallest internal diameter is adjacent to the second, opposite end of the assembly 100. This small section 114 is provided, on its internal surface, with an annular groove 115 designed to receive an O-ring seal 170 intended to ensure the seal between the two assemblies 100, 200.

Section 116 showing the internal diameter between the two sections 114, 118 mentioned above is located axially between these two above sections.

The plug 130 has the general shape of a disk extending perpendicular to the axis O-O. As previously stated, the plug 130 has a thread 132 complementary to the internal thread 119. Thus, the plug 130 can be screwed onto the first end of the body 110 to close it. The plug 130 has a through axial channel 134, for example central. This channel 134 is intended to receive an initiator 180, for pyrotechnic composition 400, for example an initiator electric.

The plug 130 is preferably provided with structures, for example a series of offset holes 136, intended to facilitate training in rotation of the plug 130 to secure it to the body 110.

It is defined at the level of the connection zone between section 118 of larger dimension and the intermediate section 116, a step 117 in the form of an annular crown transverse to the axis O-O, directed towards the first end of the assembly 100.

According to the embodiment illustrated in Figure 1, the second assembly 200 consists of a piston centered on the axis O-O. It is stepped on its outer surface.

More precisely still, according to the embodiment illustrated on the FIG. 1, the piston 200 is stepped in the form of three sections: 214, 216, 218.

Section 214 of smaller diameter is located at the level of the second end of the body 110. Its external diameter is complementary of the internal diameter of the section 114 of the body 110. The annular seal 170 aforementioned is supported on this external surface to ensure the seal between the two sets 100 and 200.

The larger diameter section 218 of the piston 200 is located at the vicinity of the first end of the body 110. The external diameter of this section 218 is between the internal diameter of the section 116 and the internal diameter of the section 118 of the body 110.

Section 216 of piston 200 is located axially between the two abovementioned sections 214, 218. It has an external diameter included between that of sections 114 and 116 of body 110.

The ring 150 is formed of two cylindrical sections 152, 156 centered around the axis O-O connected by a central ring 154 transverse to the O-O axis.

The cylindrical section 152 has an external diameter included between the internal diameter of section 118 of the body and the internal diameter of the intermediate section 116 of the body 110. The internal diameter of this cylindrical section 152 is complementary to the external diameter of the large section 218 of the piston and rests against this large section. This cylindrical section 152 is located between the recess 117 and the axial face internal of the plug 130. The axial length of the cylindrical section 152 is as it is immobilized, pinched between the two aforementioned elements, when the plug 130 is assembled on the body 110.

The second section 156 of the ring 150 has a diameter external diameter smaller than the internal diameter of section 116 and a diameter internal complementary to the external diameter of section 216 of the piston 200. It is based on the latter.

The radial extension of the intermediate ring 154 on the inside of the cylindrical section 152 is equal to the radial extension of section 218 of the piston on the outside of section 216.

Thus, the ring 150 defines in combination with the piston 200 a chamber 310 housing a volume of metal at low melting point 300.

This chamber 310 is delimited radially on the outside by the cylindrical section 152 of the ring 150, radially on the inside by the wall of the piston constituting the intermediate section 216, axially on the side first end by the large section 218 of the piston and axially side second end by the intermediate ring 154 of the ring 150.

The piston 200 is also provided with a central blind chamber 220 which opens onto the first end of the piston, opposite the electric initiator 180 and which houses the pyrotechnic composition 400.

The operation of the pyromechanism illustrated in Figure 1 is essentially the following: before implementing the electric initiator 180, and initiation of the pyrotechnic composition 400, the brazing formed by the metal with low melting point 300 located at the interfaces between parts 156 and 216 and between parts 152 and 218, as well as the phase solid of this metal 300 located in the chamber 310 ensure a secure blocking and efficient structure by ensuring relative immobilization between the two sets 100 and 200, the ring 150 being immobilized relative to the body 110 and the plug 130. It will be noted that in this position, the small section 214 of the piston 200 can emerge at least partially on outside of set 100.

The supply of the electric initiator 180 allows the triggering of pyrotechnic composition 400 and from there a rapid rise in the temperature of the metal 300 suitable for ensuring its fusion in order to release the piston 200 compared to the set 100. The gases resulting from the chemical reaction at level of pyrotechnic composition 400 cause an expansion of the chamber 220 and therefore a displacement of the piston 200 away from the plug 130 by translation along the axis O-O. This displacement of the piston 200 causes a reduction in the volume of the chamber 310, therefore a transfer of the low melting metal 300, by rolling between adjacent surfaces ring 150 and piston 200, to generate a damper function of movement.

The solidification of the metal with a low melting point 300 then makes it possible, after reconstitution of the solder, the final blocking of the device in a new state in which the extension of the piston 200 on the outside of the body 100, at its second end, is greater than the initial state.

Those skilled in the art will readily understand that such a pyromechanism constitutes an advantageous linear actuator.

Of course, different variants of the device as well described can be considered.

First, a low point metal rolling can be provided melting point 300 not at the interfaces defined between the ring 150 and the piston 200 but at the level of calibrated bores formed in the ring 150 or in the piston 200 delimiting the chamber 310.

Second, as will be described in more detail below, we may consider ensuring the displacement displacement of the piston 200, not point under the effect of gases from pyrotechnic composition 400, but under the effect of an auxiliary biasing member, for example an element spring.

Low melting metal 300 can be thermally isolated from the external environment in order to avoid any risk of melting of this metal 300 before use of pyrotechnic composition 400.

For this purpose, preferably, the body 110 and the plug 130 arranged on the outside of the chamber 310 are made of materials exhibiting poor heat conduction properties or thermally insulating, while the piston 200 whose wall forming the intermediate section 216 is inserted between the pyrotechnic composition 400 and the metal with a low melting point 300 is preferably produced in a material good thermal conductor.

Furthermore, the metal 300 must be chosen to present a higher melting or softening temperature ambient to ensure its merger only in the event of implementation of initiator 180.

We will now describe the embodiment illustrated on the figure 2.

We find in this figure, a structure composed of two assemblies 100, 200 capable of relative translation along an axis O-O, a metal with a low melting point 300 and a pyrotechnic composition 400.

At rest, the low-melting metal 300 provides a immobilization between the two assemblies 100, 200. When setting work of pyrotechnic composition 400, the metal with low melting point 300 is liquefied and the gas developed by the pyrotechnic composition 400 requests the sets 100, 200 with relative displacement. The structure is again immobilized after cooling of the metal 300. Furthermore, there again, according to the embodiment of Figure 2, the metal 300 is located in a chamber 310 defined between, on the one hand, a ring 150 immobilized between a body 110 and a plug 130, and on the other hand a piston 200. More again precisely, the chamber 310 is delimited by elements of the ring 150 and elements of the piston 200, generally in L having each an axial section and a radial section.

However, the device illustrated in FIG. 2 presents with respect to Figure 1 a number of characteristic points, among which we may cite the following.

According to Figure 2, the piston 200 is formed of an annular structure which does not directly provide the actuator output effect, but controls the output element.

More precisely, this output element is formed of a structure 230 can be formed for example of a nut, a clamp system made up of different segments, for example threads equi-distributed around the O-O axis, or any equivalent means. This forming element output actuator 230 is trapped in the initial rest position between two truncated cones 219, 139 formed respectively on the piston 200 and on the cap 130.

Furthermore, the piston 200 is formed from two parts 202, 204 assembled by thread with an interposed seal 206.

An O-ring 170 is placed in a groove 203 in the part 202 to seal between the piston 200 and the body 110, so comparable to Figure 1.

An additional seal 172 placed in a groove 137 of the plug 130 seals between the latter and the piston 200.

The initiator 180 is placed in a radial passage opposite the axis O-O passing through the wall of the body 110. The initiator 180 thus opens into an annular chamber 140 containing the pyrotechnic composition 400. This chamber 140 is delimited radially on the outside by the wall internal of the body 110, axially on the second end of the system by a transverse surface of the piston 200 and axially on the first end and radially on the inside by the ring 150.

Note also that at the second end, the body 110 has a flange 1102 directed radially inwards and comprising a sheath 1104 provided with an internal thread 1106. Such thread 1106 can receive any additional threaded element in front be temporarily maintained in relation to an associated associated element meanwhile by the thread 232 of the central element 230 formed of a nut or pliers.

The device illustrated in FIG. 2 can find application in the controlled release, during the implementation of the initiator 180, of a assembly carried out by threaded elements engaged respectively with 1106 and 232 threads.

Again, the initiation of the pyrotechnic charge 400 strongly exothermic, by the electric initiator 180, allows the metal 300 to melt low melting point, initially forming a solder between the ring 150 and the piston 200, to release the movement. The gases from combustion and of the pyrotechnic composition 400 push the piston 200 towards the second end of the structure. The liquid metal 400 is then laminated in the set of adjustments formed between the piston 200 and the ring 150, to form a damping function controlling the dynamics of the piston.

We will now describe the embodiment illustrated on the Figure 3 attached.

We find in this variant a structure comprising two sets 100, 200 susceptible of relative displacement, but immobilized initially by a metal with a low melting point 300 forming a solder, between a ring 150 linked to the first set and the second set 200 forming a piston, as well as a highly pyrotechnic composition exothermic 400 associated with an electric initiator 180.

Furthermore, here again, the first set 100 is formed by assembly of a body 110 and a plug 130.

The pyrotechnic initiator 180 is placed in a radial channel passing through the wall of the external body 110 and opens into a chamber annular 140 delimited by the body 110, the ring 150, and in its portion radially internal by the external periphery of the piston 200.

The ring 150 is also linked to the first set 100. It has for this a pinched portion between a shoulder of the body 110 and the cap 130.

The annular chamber 310 which contains the metal at low point fusion 300 forming solder, located radially on the inside of the chamber 140 and containing the pyrotechnic composition 400 is delimited by two pairs of L-shaped walls belonging respectively to the ring 150 and to the piston 200, each of these two pairs of walls having a wall 154, 218 of radial orientation transverse to the axis O-O and a wall 152, 216 axial orientation parallel to the O-O axis.

According to FIG. 3, the chamber 140 containing the composition pyrotechnic 400 being delimited only radially on the inside by the piston 200, it is understood that the gases possibly generated by the pyrotechnic composition 400 cannot stress the structure in displacement.

In this context, according to FIG. 3, the piston 200 is stressed at displacement towards the second end of the structure, after fusion of the solder 300 by an auxiliary biasing element, for example a spring. As a variant, the piston 200 can be stressed by an element outside the structure illustrated in FIG. 3, for example a strap biasing the piston 200 towards the outside of the body 110.

As mentioned above, the illustrated embodiment in FIG. 3 makes it possible inter alia to cause a relaxation between the tensioned parts such as straps, cables, etc ...

We will now describe the embodiment illustrated on the figure 4.

This repeats the general provisions illustrated in Figure 1 and previously described. However, it differs from the embodiment previously described with reference to FIG. 1 by the fact that according to FIG. 4, the structure comprises two pyrotechnic compositions 400, 410 linked together by a pyrotechnic relay 420.

The first pyrotechnic composition 400 communicates with the electric initiator 180. It is placed in an annular chamber 220 formed in the piston 200 near the metal 300, more precisely radially on the inside of the chamber 310 delimited by the ring 150 and the outer periphery of the piston 200.

This first pyrotechnic composition 400 is strongly exothermic but can generate little gas if necessary. She has for function of melting the adjacent metal 300.

The second pyrotechnic composition 410 is placed in a blind chamber 222 formed in a central position in the piston 200 and leading to the first end of the cap side structure shutter 130. The pyrotechnic delay 420 is placed in a passage radial connecting the two chambers 220, 222. Thus the second composition pyrotechnic 410 is implemented after the first composition pyrotechnic 400, according to a delay defined by the combustion of the delay pyrotechnic 420. The second pyrotechnic composition 410 is designed to generate a sufficient volume of gas to move the piston 200 as previously described with reference to FIG. 1.

The use of two pyrotechnic compositions 400, 410 intended to ensure respectively the fusion of the metal 300 and the displacement of piston 200 allows precise sequential control of functioning of the structure.

We will now describe the embodiment illustrated on the figure 5.

This variant also incorporates the general concepts illustrated in Figure 1 and described above. Furthermore, the variant of embodiment illustrated in Figure 5 also includes two compositions pyrotechnics 400, 410 intended respectively to ensure the fusion of metal 300 and the generation of clean gas to move the piston 200. However, unlike Figure 4, the two compositions pyrotechnics 400, 410 are not connected by a pyrotechnic delay. On the contrary, they are associated with initiators, for example electrical, respective, 180, 182 carried by the plug 130. In this case, the sequencing is not controlled by pyrotechnic effect due to a delay as described for figure 4, but by applying appropriate signals on the respective initiators 180, 182.

Furthermore, according to FIG. 5, in a manner comparable to FIG. 4, the first pyrotechnic composition 180 highly exothermic is located adjacent to metal 300, in an annular piston chamber 200, while the second pyrotechnic composition 410, generating gas, is located in a blind central chamber 222 of the piston 200.

Of course, the present invention is not limited to the modes of particular realization which have just been described.

In particular while according to the embodiments previously described, the device according to the present invention essentially constitutes a linear displacement actuation according to the O-O axis of the device as a variant, provision can be made for the latter to generate forces transverse to the axis O-O, for example of clamp by tightening of segments of general axial orientation equi-distributed around the axis O-O, by means, in a corner or in a cone linked to the displaced piston 200.

• Bi50/Pb28/Sn22 (pour une température de fusion de l'ordre de 95-110°C) ou
• In (pour une température de fusion de l'ordre de 156°C) ou
• Sn ou Sn85/Zn15 (pour une température de fusion de l'ordre de 200-250°C) ou
• Pb82,5/Cd17,5 ou
• Pb96/Sb4 (pour une température de fusion de l'ordre de 250-300°C),

tandis que la composition pyrotechnique 400 peut être formée de :

• Al + Fe₂O₃ ou
• Mg + Fe₂O₃ ou
• Al + CuO ou
• Mg + CuO.

By way of nonlimiting example, the metal 300 with a low melting point can be formed from:

• Bi50 / Pb28 / Sn22 (for a melting temperature of the order of 95-110 ° C) or
• In (for a melting temperature of the order of 156 ° C) or
• Sn or Sn85 / Zn15 (for a melting temperature of the order of 200-250 ° C) or
• Pb82.5 / Cd17.5 or
• Pb96 / Sb4 (for a melting temperature of the order of 250-300 ° C),

while the pyrotechnic composition 400 can be formed from:

• Al + Fe ₂ O ₃ or
• Mg + Fe ₂ O ₃ or
• Al + CuO or
• Mg + CuO.

• le métal 300 à bas point de fusion peut être remplacé par tout matériau approprié, par exemple paraffine, alliages eutectiques, etc...

Furthermore, in the context of the present invention:

• metal 300 with a low melting point can be replaced by any suitable material, for example paraffin, eutectic alloys, etc.

Claims (24)

1. A mechanism-forming device, in particular for application in space, the device comprising in combination:

   a low melting point material (300);

   at least one heater means (400); and

   means suitable for throttling the low melting point material (300) in the liquid state, after the heater means (400) have operated, thereby performing a shock-absorbing function, the device being characterized by the fact that the heater means (400) comprise at least one highly exothermal pyrotechnical composition.
2. A device according to claim 1, characterized that the fact that the low melting point metal (300) is adapted to perform soldering, and by the fact that the device further comprises a structure presenting architecture that possesses a zone that is blocked by the low melting point metal (300) and that is capable of being released by the low melting point material liquefying when the heater means are operated.
3. A device according to claim 1 or claim 2, characterized by the fact that it comprises at least two concentric surfaces (154, 216; 152, 218) provided respectively on parts (150, 200) that are capable of moving in order to throttle the low melting point material (300).
4. A device according to claim 1 or claim 2, characterized by the fact that it has at least one calibrated bore opening out into the chamber containing the low melting point material (300) for throttling purposes.
5. A device according to any one of claims 1 to 4, characterized by the fact that the pyrotechnical composition (400, 410) is designed to generate a volume of gas that is sufficient to drive relative displacement of the two parts (100, 200) of the device.
6. A device according to any one of claims 1 to 5, characterized by the fact that it has an external element, such as a resilient member of an element working in traction, suitable for driving relative displacement between the two parts (100, 200) of the device after the heater means (400) have been operated.
7. A device according to any one of claims 1 to 6, characterized by the fact that the low melting point material (300) is situated in a chamber (310) designed to be reduced in volume during operation of the heater means (400).
8. A device according to any one of claims 1 to 7, characterized by the fact that the chamber (310) housing the melting point material (300) is defined by two L-shaped structures, each possessing both an axially-extending wall (152,216) and a radially-extending wall (254, 218) secured respectively to two assemblies (100, 200) capable of relative movement.
9. A device according to claim 8, characterized by the fact that the chamber (310) housing the melting point material (300) is defined at least in part by a ring (150) secured to a fixed body (110).
10. A device according to claim 9, characterized by the fact that the ring (150) is clamped between an outer shell body (110) and a closure plug (130).
11. A device according to any one of claims 1 to 10, characterized by the fact that the chamber (310) housing the melting point material (300) is thermally insulated from the external environment.
12. A device according to any one of claims 1 to 11, characterized by the fact that it comprises an outer shell body (110) that is thermally insulating.
13. A device according to any one of claims 1 to 12, characterized by the fact that it includes a piston (200) suitable for being moved out from a shell body after the heater means (200) have been operated, thereby forming a linear actuator.
14. A device according to any one of claims 1 to 13, characterized by the fact that it has two parts (100, 230) capable of relative movement for releasing an assembly when the heater means are operated.
15. A device according to any one of claims 1 to 14, characterized by the fact that it includes a nut (230) suitable for being released when the heater means are operated.
16. A device according to any one of claims 1 to 15, characterized by the fact that it has a nut (230) made up of a plurality of segments uniformly distributed around an axis and suitable for being released when the heater means are operated.
17. A device according to any one of claims 1 to 16, characterized by the fact that it includes a clamp structure constituted by a plurality of general axially extending segments (194) uniformly distributed around an axis O-O and suitable for moving towards one another during displacement of a piston (200) having an actuator surface in the form of a truncated cone, after the heater means (400) have been operated.
18. A device according to any one of claims 1 to 17, characterized by the fact that it includes an initiator (180) associated with the heater means (400).
19. A device according to any one of claims 1 to 18, characterized by the fact that the heater means comprises two pyrotechnical compositions (400, 410), respectively one composition that is highly exothermal and another composition that generates gas, thereby respectively melting the low melting point material (300) and driving the structure.
20. A device according to claim 19, characterized by the fact that the two pyrotechnical compositions (400, 410) communicate via a pyrotechnical delay (420).
21. A device according to claim 19, characterized by the fact that the two pyrotechnical compositions (400, 410) are actuated by respective initiators (180, 182).
22. A device according to any one of claims 1 to 21, characterized by the fact that the mechanism constitutes a pyromechanism.
23. A device according to any one of claims 1 to 22, characterized by the fact that the low melting point material is a metal (300).
24. A device according to any one of claims 1 to 23, characterized by the fact that the low melting point material (300) is selected from the group comprising paraffin and eutectic alloys.

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